U.S. patent application number 10/533956 was filed with the patent office on 2006-09-14 for fishes treated with lactic acid bacterium culture medium having antibacterial and antioxidative effects.
This patent application is currently assigned to NIPPON SUISAN KAISHA LTD.. Invention is credited to Nobuhiko Doumoto, Masayuki Nasu, Takahiro Oba, Akiko Takahashi.
Application Number | 20060204618 10/533956 |
Document ID | / |
Family ID | 32310402 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060204618 |
Kind Code |
A1 |
Doumoto; Nobuhiko ; et
al. |
September 14, 2006 |
Fishes treated with lactic acid bacterium culture medium having
antibacterial and antioxidative effects
Abstract
Fish and shellfish meat whose color tone is well preserved,
particularly no Listeria contamination and in which discoloration
is effectively prevented, and smoked products prepared from such
fish and shellfish meat are provided. Fish meat which is no
Listeria contamination and in which discoloration is prevented can
be obtained by treating the meat with a cultivation medium used for
cultivating lactic acid bacteria. Specifically, the meat is
immersed preferably in a sterilized or disinfected cultivation
medium used for cultivating a lactic acid bacterium having
antibacterial and anti-oxidative effects, or two lactic acid
bacteria in combination, one having antibacterial effect and the
other anti-oxidative effect. Combinational use of Lactobacillus
sake D-1001 (FERM P-11708 or IPOD FERM BP-08544) and Lactococcus
lactis IFO 12007 is preferred. The fish meat is preferably derived
from salmon, trout or cod, and the inventive method is particularly
effective for fish meat containing astaxanthin.
Inventors: |
Doumoto; Nobuhiko; (Tokyo,
JP) ; Takahashi; Akiko; (Tokyo, JP) ; Nasu;
Masayuki; (Tokyo, JP) ; Oba; Takahiro; (Tokyo,
JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
NIPPON SUISAN KAISHA LTD.
Tokyo
JP
100-8686
|
Family ID: |
32310402 |
Appl. No.: |
10/533956 |
Filed: |
November 6, 2003 |
PCT Filed: |
November 6, 2003 |
PCT NO: |
PCT/JP03/14160 |
371 Date: |
March 22, 2006 |
Current U.S.
Class: |
426/56 |
Current CPC
Class: |
A23Y 2220/77 20130101;
A23B 4/12 20130101; A23B 4/22 20130101 |
Class at
Publication: |
426/056 |
International
Class: |
A23L 1/31 20060101
A23L001/31 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2002 |
JP |
2002-322874 |
Claims
1. A fish and shellfish meat treated with a lactic acid bacteria
cultivation medium having antibacterial and anti-oxidative effects
due to substances produced by the lactic acid bacteria.
2. A fish and shellfish meat according to claim 1 wherein the
lactic acid bacteria comprise a lactic acid bacterium having
antibacterial and anti-oxidative effects, or two lactic acid
bacteria in combination, one having antibacterial effect and the
other anti-oxidative effect.
3. A fish and shellfish meat according to claim 1 which is free
from Listeria contamination and whose color tone is preserved.
4. A fish and shellfish meat according to claim 1, wherein the
cultivation medium is sterilized or deprived of lactic acid
bacteria.
5. A fish and shellfish meat according to claim 1 wherein the
treatment comprises immersing the meat in a lactic acid bacteria
cultivation medium.
6. A fish and shellfish meat according to claim 1 wherein the
lactic acid bacteria comprise a combination of Lactobacillus sake
D-1001 (IPOD FERM PB-08544) and Lactococcus lactis IFO 12007.
7. A fish and shellfish meat according to claim 1 wherein the meat
is derived from salmon, trout or cod.
8. A fish and shellfish meat according to claim 1 wherein the meat
contains astaxanthin.
9. A fish and shellfish meat according to claim 1 wherein the meat
comprises fresh fish and shellfish meat, pasteurized fish and
shellfish meat, fresh fish eggs or pasteurized fish eggs.
10. A smoked fish and shellfish meat obtained from the fish and
shellfish meat according to claim 1.
11. An anti-oxidative agent containing a cultivation medium used
for cultivating Lactobacillus sake D-1001 (IPOD FERM BP-08544).
12. A color tone preserving agent based on the anti-oxidative
effect of a cultivation medium used for cultivating Lactobacillus
sake D-1001 (IPOD FERM BP-08544).
13. A color tone preserving agent useful for the storage of
astaxanthin-containing food products based on the anti-oxidative
effect of a cultivation medium used for cultivating Lactobacillus
sake D-1001 (IPOD FERM BP-08544).
Description
TECHNICAL FIELD
[0001] The present invention relates to fish and shellfish meat
treated with a lactic acid bacteria cultivation medium having
antibacterial and anti-oxidative effects. The present invention
also relates to fish and shellfish meat free from Listeria
contamination and in which decoloration is inhibited.
BACKGROUND ART
[0002] The conventional process of smoking fish and shellfish meat
to produce smoked fish meat (also called "smoked product") includes
immersing the fish and shellfish meat ("fish meat" hereinafter) in
a solution containing a high concentration of salt for a long time
(curing), in order to prevent the meat from being contaminated by
microbes. Generally, the curing consists of immersing the fish meat
overnight in a solution containing 15% or more salt. As a
consequence, the resulting smoked product contains a rather high
concentration of salt.
[0003] The smoked product contains 3% or more salt to avoid the
risk of microbial contamination. However, consumers want to eat
less salty smoked products, or so-called lightly-salted smoked
products. Moreover, with regard to smoked salmon meat, i.e., a
smoked product which is the most abundantly consumed in the market,
astaxanthin contained in the meat may be metabolized as a result of
oxidation or exposure to light, which causes decoloration of the
smoked salmon meat. To meet this problem, recently several attempts
have been undertaken to inhibit oxidization using an antioxidant
such as vitamin C or the like. One such attempt consists of using
orange juice to preserve the taste, flavor and color of a smoked
product (see, for example, Patent Document 1). This attempt was
undertaken with a view to utilizing vitamin C or the like contained
in orange juice as an antioxidant.
[0004] In the production of food products, a lactic acid bacteria
cultivation medium has been frequently used as a preserving agent.
Lactic acid bacteria used for this purpose largely belong to
Lactococcus lactis ssp. Lactis which produces nisin, an
antibacterial substance (see, for example, Patent Document 2). Some
other attempts use, in addition to lactic acid bacteria,
Bifidobacterium or propionic acid bacterium, expecting that organic
acids produced by the latter bacterium may have some additional
antibacterial effect (see, for example, Patent Documents 3 and 4).
Although those bacterial species are known to be antibacterial to
pathogenic bacteria, their anti-oxidative effect has not been
documented.
[0005] An example involving the use of lactic acid bacteria in the
production of fish meat products uses salt and fermented milk (see
Patent Document 5).
[0006] Patent Document 1: Japanese Unexamined Patent Application
Publication No. 6-38674
[0007] Patent Document 2: Japanese Unexamined Patent Application
Publication No. 8-187071
[0008] Patent Document 3: Japanese Unexamined Patent Application
Publication No. 7-51038
[0009] Patent Document 4: Japanese Unexamined Patent Application
Publication No. 8-187072
[0010] Patent Document 5: Japanese Unexamined Patent Application
Publication No. 5-308895
DISCLOSURE OF THE INVENTION
[0011] Fish meat products such as smoked ones obtained by
conventional methods including no sterilization have the risk of
being contaminated by Listeria bacteria or the like. Moreover, with
regard to smoked salmon meat, pigments in the meat such as
astaxanthin are decolored due to oxidization or exposure to light,
which may lower the marketing value of the meat. An object of the
present invention is to provide fish meat products which are less
likely to be contaminated by bacteria and whose color tone is
preserved, particularly fish meat products which is not
contaminated by Listeria species and whose color tone is
preserved.
[0012] One feature of the present invention is fish meat treated by
"a lactic acid cultivation medium in which lactic acid bacteria
were cultivated" ("lactic acid cultivation medium" hereinafter),
which has antibacterial and anti-oxidative effects due to
substances produced by the lactic acid bacteria.
[0013] The lactic acid bacteria may consist of a strain having
antibacterial and anti-oxidative effects, or a combination of a
strain having antibacterial effect and another strain having
anti-oxidative effect. In this connection, another feature of the
present invention is fish meat treated by lactic acid cultivation
medium, which has antibacterial and anti-oxidative effects due to
substances produced by a lactic acid bacterium having antibacterial
and anti-oxidative effects, or two lactic acid bacteria cultivated
in combination, one having antibacterial effect and the other
anti-oxidative effect.
[0014] The above fish meat is free from Listeria contamination, and
its color tone is preserved. In this connection, yet another
feature of the present invention is fish meat free from Listeria
contamination and whose color tone is preserved by treating the
meat with a lactic acid bacteria cultivation medium which has
antibacterial and anti-oxidative effects due to substances produced
by the lactic acid bacteria, preferably by a lactic acid bacterium
having antibacterial and anti-oxidative effects, or by two lactic
acid bacteria cultivated in combination, one having antibacterial
effect and the other having anti-oxidative effect.
[0015] The above lactic acid bacteria cultivation medium is
sterilized or disinfected. In this connection, yet another feature
of the present invention is fish meat preferably free from Listeria
contamination and whose color tone is preserved by treating the
meat with a sterilized or disinfected lactic acid bacteria
cultivation medium which has antibacterial and anti-oxidative
effects due to substances produced by the lactic acid bacteria,
preferably by a lactic acid bacterium having antibacterial and
anti-oxidative effects, or two lactic acid bacteria cultivated in
combination, one having antibacterial effect and the other
anti-oxidative effect.
[0016] The treatment consists of immersing fish meat in a lactic
acid bacteria cultivation medium. In this connection, yet another
feature of the present invention is fish meat preferably free from
Listeria contamination and whose color tone is preserved by
immersing the meat preferably in a sterilized or disinfected
cultivation medium which has antibacterial and anti-oxidative
effects due to substances produced by the lactic acid bacteria,
preferably by a lactic acid bacterium having antibacterial and
anti-oxidative effects, or two lactic acid bacteria cultivated in
combination, one having antibacterial effect and the other
anti-oxidative effect.
[0017] The lactic acid bacteria mentioned above include
Lactobacillus sake D-1001 (preserved initially as a domestic
deposit under the ID code of FERM P-11708, then transferred to
International Patent Organism Depository, National Institute of
Advanced Industrial Science and Technology (Tsukuba Central 6,
1-1-1, Higashi, Tsukuba, Ibaraki, Japan) on Nov. 6 2003 and
preserved there as an international deposit under the ID code of
IPOD FERM BP-08544), and Lactococcus lactis IFO 12007. In this
connection, yet another feature of the present invention is fish
meat preferably free from Listeria contamination and whose color
tone is preserved preferably by immersing the meat preferably in a
sterilized or disinfected cultivation medium which has
antibacterial and anti-oxidative effects due to substances produced
by the lactic acid bacteria, preferably by Lactobacillus sake
D-1001 (FERM P-11708 or IPOD FERM BP-08544) and Lactococcus lactis
IFO 12007 cultivated in combination, i.e., a lactic acid bacteria
having antibacterial and anti-oxidative effects,.
[0018] The present inventors found that Lactobacillus sake D-1001
(FERM P-11708 or IPOD FERM BP-08544) is a lactic acid bacterium
capable of producing substances that exhibit not only high
sterilizing effect against gram-positive pathological bacteria such
as Listeria etc., but also high anti-oxidative effect which
protects pigments such as astaxanthin in fish meat from
decoloration which might otherwise occur as a result of
oxidization.
[0019] A feature of the present invention is an anti-oxidative
agent containing a cultivation medium used for cultivating
Lactobacillus sake D-1001 (FERM P-11708 or IPOD FERM BP-08544).
Another feature of the present invention is a
decoloration-preventing agent based on the anti-oxidative effect of
a cultivation medium used for cultivating Lactobacillus sake D-1001
(FERM P-11708 or IPOD FERM BP-08544), particularly a
decoloration-preventing agent useful for the production of
astaxanthin-containing food products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a graph demonstrating an advantage of the
present invention, i.e., anti-oxidative effect, the graph plotting
the absorption of oxygen as a function of the days of storage.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021] The present invention utilizes a cultivation medium used for
cultivating a lactic acid bacterium having antibacterial and
anti-oxidative effects, or two lactic acid bacteria in combination,
one having antibacterial effect and the other anti-oxidative
effect. Therefore, lactic acid bacteria to be used according to the
invention are not limited to any specific lactic bacteria, as long
as they have antibacterial and/or anti-oxidative effects. A lactic
acid bacterium having antibacterial and anti-oxidative effects may
be used. However, combinational use of a lactic acid bacterium
having high antimicrobial effect and another lactic acid bacterium
having high anti-oxidative effect is rational and more preferred.
The usefulness of a lactic acid bacterium for the method of the
invention is not determined solely by its antibacterial effect or
anti-oxidative effect. Its having no adverse effect on the taste
and flavor of the resulting fish meat products is also
important.
[0022] Suitable lactic acid bacteria to be used in the invention
include lactic acid bacteria that can destroy common bacteria
through antibacterial substances such as bacteriocins and lactic
acid they produce during lactic acid fermentation, e.g., lactic
acid bacteria belonging to the genera Leuconostoc, Lactobacillus,
Lactococcus, Pediococcus, etc. It may also be possible to isolate a
novel microorganism belonging to the above genera from a food
product, and use it according to the method of the invention.
[0023] Since the material to be used in the present invention
consists of fish meat, it is preferable to use lactic acid bacteria
that have high antibacterial effect against gram-positive
pathogenic bacteria such as Listeria bacteria, and high
anti-oxidative effect so that pigments such as astaxanthin
contained in the fish meat can be prevented from decoloration which
might otherwise occur as a result of oxidization. For example,
combinational use of Lactobacillus sake D-1001 (FERM P-11708 or
IPOD FERM BP-08544) and Lactococcus lactis IFO 12007 is preferred.
Combinational use of Lactobacillus sake D-1001 (FERM P-11708 or
IPOD FERM BP-08544), which has a high anti-oxidative effect, and
Lactococcus lactis IFO 12007, which has a high antibacterial
effect, is also preferred because it not only prevents the
development of a foul odor due to putrefaction resulting from
microbial contamination or to oxidation, but does not have any
adverse effect on the taste and flavor of the treated food.
[0024] The antibacterial effect of a lactic acid bacterium against,
for example, a Listeria bacterium can be evaluated by the disc
method. Suitable lactic acid bacteria with regard to antibacterial
effect can be selected according to the evaluation results obtained
from candidate lactic acid bacteria. The anti-oxidative effect of a
lactic acid bacterium can be evaluated based on its AV (acid value)
and POV (peroxide value). Suitable lactic acid bacteria with regard
to anti-oxidative effect can be selected according to the
evaluation results obtained from candidate lactic acid
bacteria.
[0025] Cultivation of lactic acid bacteria may occur in any medium,
as long as the medium allows the growth of the bacteria therein.
However, use of a medium containing sugars at 2% or more and
proteins at 2% or more is preferred. For example, a dairy product
can be used as a medium. However, a simple medium selected
appropriately according to a given purpose is more preferred
because the coexistence of any unnecessary substances may have some
adverse effect on fish meat treated by the medium: for example, the
flavor characteristic of a diary product may affect the flavor of
the treated fish meat, or a particular ingredient in the dairy
product absorbed into the fish meat may act as an allergen.
[0026] Sterilization of lactic acid bacteria is achieved by
heating. The heating temperature is not limited to any specific
range, as long as it is sufficiently high to destroy lactic acid
bacteria. However, sterilization preferably occurs by
pasteurization consisting of heating at 65.degree. C. for 30
minutes. Disinfection of a lactic acid bacteria cultivation medium
occurs, for example, by filtration through a membrane having a pore
size of 0.22.mu..
[0027] Fish meat treated by the method of the invention is free
from Listeria contamination because the fish meat is treated with a
lactic acid bacteria cultivation medium, and the color tone is
protected against decoloration. Fish meat may be derived from any
fish including their eggs such as salmon, blue grenadier, saurel,
tuna, bonito, cod, etc.; cephalopods such as squid, octopus, etc.;
crustacea such as shrimp, krill, etc.; and shellfish, etc., and is
not limited to any specific fish or marine organisms. However,
illustrative preferred fish include salmon, trout and cod.
[0028] To produce high quality fish meat products, the number of
common bacteria inhabiting the fish meat is preferably 10.sup.3 or
lower. The lactic acid bacteria cultivation medium of the invention
is, because of its high anti-oxidative effect, effective in
inhibiting the decoloration of pigments which would otherwise occur
as a result of oxidization, and is particularly useful in
maintaining the color tone of fish meat obtained from salmon, which
is rich in astaxanthin or a pigment which is readily decolored as a
result of oxidation. Illustrative fish to which the present
invention is specifically directed are fish whose meat is rich in
astaxanthin.
[0029] The method of the invention can be applied to fresh and
pasteurized fish meat, and fresh and pasteurized fish eggs, is
profitably applied to fresh fish meat slices, e.g., sashimi, and is
particularly profitably employed in the production of smoked fish
meat products requiring long-term storage safety. A preferred
embodiment of the invention is a smoked product obtained from fish
meat which has been treated by cultivation medium used for
cultivating a lactic acid bacterium having antibacterial and
anti-oxidative effects, or two lactic acid bacteria cultivated in
combination, one having antibacterial effect and the other
anti-oxidative effect.
[0030] Suitable shapes of the fish meat to which the method of the
invention is applied are not limited to any specific ones, but
preferably include, for example, fillets, slices, etc.
[0031] According to the method of the invention, the lactic acid
cultivation medium is preferably sterilized or disinfected.
According to the method of the invention, preferably fish meat or a
material of a food product is immersed in a solution prepared as
described below, and kept there at a low temperature equal to or
lower than 10.degree. C., the solution being obtained by
inoculating lactic acid bacteria in an appropriate medium to grow
therein, and sterilizing or disinfecting the resulting cultivation
medium. As a result of these procedures, pathogenic bacteria such
as Listeria species are destroyed, and anti-oxidative substances
contained in the solution permeate through the fish meat, which
enables the production of fish meat in which decoloration is
inhibited. Treatment using a lactic acid cultivation medium may
occur by way of injection, spreading, spraying, etc., in addition
to immersion, and is not limited to any specific manner of
application, as long as that manner of application allows the fish
meat to be exposed to the lactic acid bacteria cultivation medium
at a specified concentration or higher.
[0032] A general smoking process for fish meat including the
treatment with a lactic acid bacteria cultivation medium according
to the invention consists of immersing fish meat in a cultivation
medium used for cultivating a lactic acid bacterium having
antibacterial and anti-oxidative effects, or two lactic acid
bacteria, one having antibacterial effect and the other having
anti-oxidative effect, and smoking and drying the thus treated fish
meat to produce a smoked fish meat product excellent in storage
safety. The process is specified as follows. Fish meat serving as a
starting material may be fresh or frozen, but the material should
be handled with the utmost care in order to prevent microbial
contamination as much as possible. Edible meat blocks prepared from
fish or shellfish are used as they are. On the other hand, lactic
acid bacteria are cultivated to grow to about 10.sup.9/g. The
lactic acid bacteria cultivation medium is subjected to
pasteurization at a low temperature to destroy lactic acid bacteria
therein, or lactic acid bacteria are removed by filtration through
a membrane. It is possible not only to destroy common bacteria
contaminating the fish meat material but also to prevent the
discoloration of the fish meat material by immersing the meat
material in a sterilized (or disinfected) lactic acid bacteria
cultivation medium kept at 10.degree. C. or lower for 30
minutes.
[0033] The density of lactic acid bacteria contained in a crude
lactic acid cultivation medium should be chosen as appropriate
according to a given purpose and the size of the material, but is
preferably about 10.sup.5 to 10.sup.9/g.
[0034] After being immersed in the lactic acid bacteria cultivation
solution, the fish meat material is smoked, and dried with the
temperature and humidity controlled. This step may be carried out
by any given common method, and is not limited to any specific one.
The resulting smoked fish meat product is so excellent in long-term
storage safety due to antibacterial substances produced by lactic
acid bacteria that it can be safely stored at normal temperature,
or chilled or frozen depending on its dry or moist state.
[0035] The method of the present invention applied herein will be
detailed by means of examples, but the present invention applied
herein is not limited by these examples.
EXAMPLE 1
[0036] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. On the other hand, a mixture comprising Lactococcus
lactis 12007 and Lactobacillus sake D-1001 was allowed to grow on a
medium containing, for every 1 l of water, 10 g of salt, 10 g of
glucose, 10 g of yeast extract and 30 g of soybean protein for 24
hours to give a density of 10.sup.9 cells/g, and the cultivation
medium was sterilized by being heated at 65.degree. C. for 30
minutes. The meat portions were immersed in the sterilized solution
at 10.degree. C. for 30 minutes. Then, the meat portions were dried
at 20.degree. C. for two hours, and smoked for four hours to
produce smoked salmon meat.
[0037] As Reference Examples, similar smoked salmon meat samples
were prepared in the same manner as in Example 1 except that they
were exposed to either of two cultivation media, one of which had
been used for cultivating Lactococcus lactis 12007 alone and the
other for cultivating Lactobacillus sake D-1001 alone.
COMPARATIVE EXAMPLE 1
[0038] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. Then, the meat portions were dried at 20.degree. C.
for two hours, and smoked for four hours to produce smoked salmon
meat.
[0039] The bacteriological test results of smoked salmon samples
obtained in Example 1, Reference Examples and Comparative Example 1
are shown in Table 1. In another test, smoked salmon samples
obtained in Example 1, Reference Examples, and Comparative Example
1 were evaluated based on the sensation characteristics of a panel
of 15 well-trained testers. For each test item, the tester
evaluated a test sample in comparison with a corresponding
comparative sample (0 score), and gave a score of -4 to +4 to the
test sample according to how worse or better it is when evaluated
in comparison with the comparative sample. The scores of the 15
testers were summed and averaged for the test sample. The results
are shown in Table 2. TABLE-US-00001 TABLE 1 Density of common
bacteria (cells/g) Days of Reference Reference Comparative storage
Example 1 (12007) (D1001) Example 1 0 0 0 0 <300 (0) 20 0 0 0
<300 (0) 40 0 0 3.5 .times. 10.sup.2 2.1 .times. 10.sup.4
[0040] As shown in Table 1, the smoked salmon sample treated by a
cultivation medium used for cultivating Lactococcus lactis 12007
was found to be no common bacteria even when tested on the 40th day
of storage. TABLE-US-00002 TABLE 2 Reference Reference Comparative
Test item Example 1 (12007) (D1001) Example 1 Taste 0 .+-. 0.1 0
.+-. 0.1 0 .+-. 0.2 0 Flavor 0 .+-. 0.1 0 .+-. 0.1 0 .+-. 0.2 0
Saltiness 0 .+-. 0.2 0 .+-. 0.3 0 .+-. 0.1 0 Texture 0 .+-. 0.2 0
.+-. 0.2 0 .+-. 0.2 0 Free from 0 .+-. 0.2 0 .+-. 0.2 0 .+-. 0.3 0
foreign taste & odor
[0041] As shown in Table 2, the smoked salmon sample prepared in
Example 1 was practically the same as the sample prepared in
Comparative Example 1 in its taste, flavor and texture, suggesting
that treatment consisting of immersing the test sample in a
sterilized lactic acid cultivation medium did not have any adverse
effect on the quality of the test smoked salmon sample.
EXAMPLE 2
[0042] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. On the other hand, a mixture comprising Lactococcus
lactis 1207 and Lactobacillus sake D-1001 was allowed to grow on a
medium containing, for every 1 l of water, 10 g of salt, 10 g of
glucose, 10 g of yeast extract and 30 g of soybean protein for 24
hours to give a density of 10.sup.9 cells/g, and the cultivation
medium was sterilized by being heated at 65.degree. C. for 30
minutes. The meat portions were immersed in the sterilized solution
at 10.degree. C. for 30 minutes. A culture containing Listeria
monocytogenes at 10.sup.3 cfu/g was inoculated. Then, the meat
portions were dried at 20.degree. C. for two hours, and smoked for
four hours to produce smoked salmon meat. The smoked salmon meat
was vacuum-packed in a sealed bag, and stored at 10.degree. C.
COMPARATIVE EXAMPLE 2
[0043] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. A culture containing Listeria monocytogenes at
10.sup.3 cfu/g was inoculated. Then, the meat portions were dried
at 20.degree. C. for two hours, and smoked for four hours to
produce smoked salmon meat. The smoked salmon meat was
vacuum-packed in a sealed bag, and stored at 10.degree. C.
[0044] The bacteriological test results of smoked salmon samples
obtained in Example 2 and Comparative Example 2 and stored at
30.degree. C. for 24 hours are shown in Table 3. TABLE-US-00003
TABLE 3 Density of Listeria bacteria (cells/g) Hours of Reference
Reference Comparative storage Example 2 (12007) (D1001) Example 2 0
0 0 2.0 .times. 10.sup.1 2.0 .times. 10.sup.2 24 0 0 2.0 .times.
10.sup.3 2.8 .times. 10.sup.6
[0045] As seen from Table 3, the smoked salmon samples treated by
cultivation media used for cultivating at least Lactococcus lactis
12007 were found to be no common bacteria even when they had
received the inoculation of Listeria bacteria.
EXAMPLE 3
[0046] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. On the other hand, a mixture comprising
Lactobacillus sake D-1001 and Lactococcus lactis 12007 was allowed
to grow on a medium containing, for every 1 l of water, 10 g of
salt, 10 g of glucose, 10 g of yeast extract and 30 g of soybean
protein for 24 hours to give a density of 10.sup.9 cells/g, and the
cultivation medium was sterilized by being heated at 65.degree. C.
for 30 minutes. The meat portions were immersed in the sterilized
solution at 10.degree. C. for 30 minutes. Then, the meat portions
were dried at 20.degree. C. for two hours, and smoked for four
hours to produce smoked salmon meat.
COMPARATIVE EXAMPLE 3
[0047] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed,
washed with running water, and divided into two equal meat portions
and a central spinal column portion. The meat portions were
immersed in an aqueous solution of 15% salt overnight, and rinsed
with running water for 30 minutes to remove excess salt from the
meat portions. Then, the meat portions were dried at 20.degree. C.
for two hours, and smoked for four hours to produce smoked salmon
meat.
[0048] The L-values of the smoked salmon samples obtained in
Example 3 and Comparative Examples 3 were plotted over time to
trace the temporal change of the color tone of the samples.
TABLE-US-00004 TABLE 4 L-value Days of Reference Reference
Comparative storage Example 3 (12007) (D1001) Example 3 0 44.76
43.87 44.27 44.77 14 45.27 45.32 45.67 49.27
[0049] As seen from Table 4, the increment of L-value over time was
more effectively inhibited in the sample obtained in Example 3 than
in the sample of Comparative Example 3. When the samples were
treated either with Lactococcus lactis 12007 or Lactobacillus sake
D-1001, the increment of L-value over time was more effectively
inhibited than in the sample of Comparative Example 3, but
Lactobacillus sake D-1001 inhibited the increment in question more
effectively than Lactococcus lactis 12007. The increment of L-value
over time was markedly inhibited when the sample was treated with a
mixture comprising the two strains. The above observation was also
visually confirmed: the sample of Comparative Example 3 looked
slightly bleached while the sample of Example 3 indicated very
limited bleaching, that is, it hardly underwent decoloration.
EXAMPLE 4
[0050] Frozen trout (Nippon Suisan Kaisha Ltd. product) was thawed
and washed with running water, and 25 g of meat was removed. A 5 g
of the meat was homogenized with a food cutter, and a 2 g sample of
the meat homogenate was transferred to a gas-chromatography vial
with a cap. On the other hand, lactic acid bacteria were grown on a
TSB medium at 30.degree. C. for 24 hours. A 100-.mu.l aliquot of
the culture medium was inoculated to a meat homogenate sample (test
sample). As a control, a 100-.mu.l aliquot of TSB medium instead of
the culture medium was inoculated to another meat homogenate sample
(control sample). The samples were kept at 10.degree. C. in a dark
place. The oxygen content in the head space of each vial was
determined at regular intervals by gas chromatography. As shown in
FIG. 1, the temporal reduction of oxygen content in the head space
of the vial is more effectively inhibited in the sample inoculated
by Lactobacillus sake D-1001 than in the other samples, suggesting
that treatment using Lactobacillus sake D-1001 inhibits
oxidization.
INDUSTRIAL APPLICABILITY
[0051] According to the present invention, it is possible to
provide fish meat which is less likely to suffer from microbial
contamination, and whose color tone is preserved more effectively
than conventionally treated fish meat by treating the meat with a
lactic acid bacterium having antibacterial and anti-oxidative
effects. Particularly, it is possible according to the present
invention to provide fish meat free from Listeria contamination and
whose color tone is preserved. It is possible to provide high
quality fish meat by using Lactobacillus sake D-1001 (FERM P-11708
or IPOD FERM BP-08544) and Lactococcus lactis IFO 12007 in
combination as lactic acid bacteria having antibacterial and
anti-oxidative effects without affecting the taste and flavor of
the meat. It is further possible to provide fish meat devoid of
pathogenic bacteria such as Listeria bacteria and whose color tone
is well preserved by treating the meat with a sterilized or
disinfected culture medium used for cultivating lactic acid
bacteria.
[0052] Smoked salmon meat obtained by the inventive method
comprising treating salmon meat with a sterilized cultivation
medium used for cultivating lactic acid bacteria having
antibacterial and anti-oxidative effects, and smoking and drying
the resulting salmon meat is excellent bacteriologically, in color
and in long-term storage safety.
* * * * *